added format_digest

This is the inverse of parse_digest_response and also supports escaping
of backslashes and quotes.

1 files changed, 15 insertions, 2 deletions

diff --git a/wsgitools/digest.py b/wsgitools/digest.py
index 964fa0a..83fbd65 100644
--- a/wsgitools/digest.py
+++ b/wsgitools/digest.py
@@ -114,6 +114,19 @@ class AuthenticationRequired(Exception):
 class ProtocolViolation(AuthenticationRequired):
     pass
 
+def format_digest(mapping):
+    """internal
+
+    @type mapping: {str: str}
+    @rtype: str
+    """
+    assert isinstance(mapping, dict)
+    result = ((key, value if value.isalnum() else
+                    '"%s"' % value.replace('\\', '\\\\').replace('"', '\\"'))
+              for key, value in mapping.items())
+    result = map("%s=%s".__mod__, result)
+    return ", ".join(result)
+
 class StaleNonce(AuthenticationRequired):
     pass
 
@@ -752,7 +765,7 @@ class AuthDigestMiddleware:
                     digest["qop"] = "auth"
                     digest["cnonce"] = credentials["cnonce"] # no KeyError
                     digest["rspauth"] = self.auth_response(credentials, "")
-                challenge = ", ".join(map('%s="%s"'.__mod__, digest.items()))
+                challenge = format_digest(digest)
                 headers.append(("Authentication-Info", challenge))
                 return start_response(status, headers, exc_info)
             return self.app(environ, modified_start_response)
@@ -806,7 +819,7 @@ class AuthDigestMiddleware:
                       qop="auth")
         if isinstance(exception, StaleNonce):
             digest["stale"] = "TRUE"
-        challenge = ", ".join(map('%s="%s"'.__mod__, digest.items()))
+        challenge = format_digest(digest)
         return ("WWW-Authenticate", "Digest %s" % challenge)
 
     def authorization_required(self, environ, start_response, exception):